I have searched and can't find a report of this bug, but I have render distance set to 5 and that could be the difference. I created one of the new boats, but when I row out to sea chunks don't get loaded and I fall off the edge of the world.

Steps to re-create:
Create a world with plenty of sea (eg seed -8490482450382478731)
Craft a boat
Get in. Wonder if you'll ever get used to the new controls
Row out to sea and watch the horizon get closer and closer. If you go over the edge you are thrown out of the boat. If you get out the boat chunks start loading.